It’s no secret hydraulic fracturing has unlocked enormous new supplies of natural gas in the United States. And a new report released today by the Colorado School of Mines’ Potential Gas Committee (PGC) quantifies just how much natural gas the U.S. might be able to recover moving forward — a jaw-dropping 3,100 trillion cubic feet (Tcf).

That’s the total technically recoverable amount of gas in the U.S. (reserves and known resources), according to the PGC report, which was produced in coordination with the American Gas Association (AGA). That figure represents a 12 percent increase in predicted reserves over PGC’s 2014 report and represents a record high assessment of American natural gas potential by the PGC’s team of geoscientists and engineers, who have conducted biennial studies since 1964 and are the only group that assesses future supplies of natural gas in the U.S.

Of that nearly unimaginable quantity, 2,817 Tcf has yet to be developed but is technically recoverable, based on geologic conditions and data from currently proven reserves. A further 300 Tcf is already proven or developed, according to the report, Potential Gas Supply of Natural Gas in the United States.

For reference, the U.S. consumed less than 27.5 Tcf of gas last year, meaning that our reserves could last decades if not centuries, as the Washington Examiner noted,

“To lend some perspective, the U.S. consumed about 27 Tcf of natural gas in 2016, according to the Energy Information Administration. The new number from the committee would support that rate of consumption for about 104 years.”

That’s good news for the environment as well, since clean burning American natural gas has been increasingly used for electricity generation, a major factor in the U.S. reducing carbon emissions to their lowest levels since 1991.

Shale gas represents 64 percent of the reserves detailed in the report and is behind almost all of the increase in technically recoverable resources. Vast improvements in hydraulic fracturing technology have opened up some of the world’s largest gas reserves, which could not have been exploited economically just a decade ago, as the following chart from the report indicates.

The report broke those reserves down into four categories. Proven reserves are already producing or confirmed. Probable reserves are formations in proven fields with similar geologic conditions to proven formations or discovered resources that have not yet been confirmed. Possible reserves are those in promising but unexplored formations in producing areas, and speculative reserves are those in new areas with less promising formations but that still could feasibly exist. A breakdown of each category is detailed in the chart below.

Though the report only looked at technically recoverable reserves, if even a small fraction can be recovered economically, it represents decades more of gas than previously thought.

The report highlights the Atlantic region as the most promising area for gas, in large part due to the mammoth Marcellus formation that underlies much of the Appalachian Basin and contains vast proven and probable reserves. The report also notes that Ohio’s Utica Shale “is now assessed to have a considerably larger sweet spot area with highly productive wells.”

These reserves are already powering much of the East Coast and South, allowing low cost energy for manufacturing and providing enormous supplies of feedstocks for high tech chemical refining.

The PGC’s numbers also paint a rosy picture for coal bed methane, particularly in Alaska and the Rocky Mountains where even previously mined coal seams may one day provide substantial supplies of cleaner burning natural gas.

In the near future, though, it is shale gas that is set to dominate. The effects of this unprecedented boom are being felt across the economy. From the booming Gulf Coast economy to the enormous expansion of U.S. LNG production, consumers and companies are feeling the benefits.

This new report means even more reason to be optimistic about American energy potential, not just for consumers but for the millions of Americans employed in an increasingly efficient gas industry that has brushed aside low commodity prices and international competition again and again.